Marion, Countess Yorck von Wartenburg, who has died in Berlin aged 102, was one of the last survivors of the Kreisauer Kreis (or Kreisau circle) of aristocrats, academics, senior civil servants and other leaders of pre-Nazi society whose ideas for a democratic regeneration of postwar Germany cost them their lives.

The group took its name from the Kreisau estate, now in Polish Silesia, of Helmuth James Count von Moltke, who formed it with von Wartenburg's husband, Peter Count Yorck von Wartenburg, in 1940. Both were descended from Prussian field marshals whose victories over the French in the 19th century laid the foundations for the unification of Germany in 1870-71 and its emergence as the leading European economic and military power.

The circle, which usually met on the estate, is commonly described as part of the resistance to Hitler, which most historians agree did not amount to much. Its members described the circle as no more than a discussion group, expressly opposed to a coup d'état or political violence. Yet in Nazi Germany even that amounted to treason.

There is no denying the moral and physical courage of Kreisauer members, so many of whom were horribly executed for their beliefs. As Count Yorck wrote in his last letter to Marion before his execution in August 1944: "I believe I have gone some way to atone for the guilt which is our heritage."

Appalled by Hitler and the Nazi stain on the name of Germany, the members took it as read that he would be defeated by the Allies in the second world war, and agonised over the utopian shape of a democratic, Christian-socialist state that would rise from the ruins. It was a very German manifestation of idealism, and even mysticism, that had nothing to say about how the Germans themselves might make a practical contribution to their own salvation by deposing the regime the group blamed for their country's plight. As William Shirer, historian of the Third Reich, wrote: "Moltke and his friends had the courage to talk - for which they were executed - but not to act."

Marion Winter was born in Berlin, the daughter of a senior civil servant responsible for the German state's role in supporting the performing arts. After school in her home city, she went on to university there to study medicine, but switched to law, in which she gained a doctorate at the age of 25. Unusually for a woman at the time, she started training as a judge, a career separate from advocacy in Germany.

In 1930, however, she married Peter Yorck, a year older, whom she had met while they were both studying law. Although her background was upper middle class, Marion's marriage to a landed aristocrat from a family with several estates (awarded to the field-marshal ancestor) led her to give up the law and help with the progressive management of the estate that her husband took over from his brother, who was killed in action in 1942.

Although opposed to violence, Kreisau members inevitably came into contact and conversed with the military plotters who were bent on deposing Hitler by force and had made several ineffectual attempts on his life. Peter Yorck was working in the war office, where Claus Count von Stauffenberg and other army officers were planning to assassinate Hitler with a bomb at his headquarters at Rastenburg on July 20 1944 and take over power using the home army. The military plotters were largely motivated by Germany's impending defeat and wanted to prevent Hitler taking the country down with him. But he miraculously survived the blast and took a terrible revenge on all those involved or suspected of involvement - including anyone who had dared to question the regime, such as the Kreisau circle.

Peter Yorck was one of the first to be subjected to the travesty of a show trial and executed. Within days of his death, Marion was arrested and put in solitary confinement for three months. Released without charge, she managed to get to the Yorck estates, which were soon overrun by the advancing Red Army. Although she eluded the attentions of Soviet soldiers, she was jailed again in Poland for another three months and beaten up by communist guards who refused to accept that she was not a Nazi.

After the war, Marion Yorck went back to being a judge, helped by her record as an anti-Nazi, and acquired a reputation as fair but firm in the criminal trials she supervised. She advanced to a position as a judge in the Berlin state high court, and in 1984 wrote a short memoir.

The Yorcks had no children and Marion did not remarry, keeping the Yorck family name in honour of her husband. But for half a century she lived with the Christian Democrat lawyer Ulrich Biel, another anti-Nazi, who died in 1996.